A radiuscope is more beneficial for determining which GP lens issue?

• A. Flexure (on-eye)
• B. Warpage (off-eye)
• C. Tear film break-up
• D. Edge lift

Answer: (B)

The radiuscope is used to measure the back surface radius of a gas-permeable lens when the lens is off the eye, so it directly checks the actual shape of the lens itself. If the lens has warped, processing or handling can alter its back-curvature, and this shows up as a deviation from the intended radius on the radiuscope. That makes it particularly useful for detecting warpage off the eye, where the lens’ shape changes are isolated from the eye’s surface.

On-eye flexure is a dynamic phenomenon caused by blinking and eyelid pressure, best evaluated during wear with observation and fluorescein, not by a static off-eye measurement. Tear film break-up concerns the corneal surface rather than the lens’ back geometry, so the radiuscope won’t diagnose tear-film issues. Edge lift involves the lens edge behavior at the periphery, which is better assessed by slit-lamp inspection and edge-fit analysis rather than measuring the back surface radius.